Mohon bantuannya, setelah saya berhasil melakukan upload dan update gambar baru, file yang lama masih ada dalam folder assets padahal sudah pakai unlink tapi tetap gk ada efek di file tersebut ini Controllernya:

 public function det_dosen()
    {
        if($this->session->userdata('akses') =='1'){ 
            $id_login   = $this->input->post('id_login');
            $prodi    = $this->input->post('prodi');
            $jenjang  = $this->input->post('jenjang');
            $ttl      = $this->input->post('ttl');
            $email    = $this->input->post('email');
            $notelp   = $this->input->post('no_telp');
            $alamat   = $this->input->post('alamat');
            $foto = $_FILES['fotopost ']['name'];    
            $old = $this->input->post('fotolama');               

            if (empty($foto)){
                $config['upload_path']      = './assets/img/profile';
                $config['allowed_types']    = 'jpg|png|jpeg';
                $config['max_size']        = 2048;

                $this->load->library('upload',$config);
                $this->upload->initialize($config);
                if(!$this->upload->do_upload('fotopost')){
                    echo $this->upload->display_errors(); die();
                }
                else{
                    $foto = $this->upload->data('file_name');                
                }

                $data = array(      
                    'prodi'         => $prodi,
                    'jenjang_pend'  => $jenjang,
                    'alamat'        => $alamat,
                    'ttl'           => $ttl,
                    'no_telp'       => $notelp,
                    'email'         => $email,                                                                   
                    'profile'       => $foto 
                );               
                $this->m_admin->input_detdosen($id_login, $data);
            }
            else{
                $config['upload_path']      = './assets/img/profile';
                $config['allowed_types']    = 'jpg|png|jpeg';
                $config['max_size']        = 2048;

                $this->load->library('upload',$config);
                $this->upload->initialize($config);
                if(!$this->upload->do_upload('fotopost')){
                    echo $this->upload->display_errors(); die();
                }
                else{
                    $foto = $this->upload->data('file_name');                
                }

                $data = array(      
                    'prodi'         => $prodi,
                    'jenjang_pend'  => $jenjang,
                    'alamat'        => $alamat,
                    'ttl'           => $ttl,
                    'no_telp'       => $notelp,
                    'email'         => $email,                                                                   
                    'profile'       => $foto
                );
               $path = './assets/img/profile/'.$old;
                unlink($path);
                
                $this->m_admin->input_detdosen($id_login, $data);            
            }                      
            redirect('admin/show_dosen/'.$id_login);             
                                
        }else{
            redirect('login');
        }                                
    } 

Dan ini Model:

function input_detdosen($id_login, $data){	
        $this->db->where('id_login',$id_login);
        return $this->db->update('data_dosen', $data);  
    }

Input di index:

<input type="hidden" name="fotolama" value="<?php echo $ds['profile'];?>">
<input type="file" name="fotopost" class="form-control">